Optics
Myopia (near-sighted)
A near-sighted eye can't relax enough to focus distant objects — the image falls in front of the retina, so it looks blurred.
Myopia (near-sighted) — interactive Optics simulation. A near-sighted eye can't relax enough to focus distant objects — the image falls in front of the retina, so it looks blurred.
Myopia
A near-sighted eye can't relax enough to focus distant objects — the image falls in front of the retina, so it looks blurred.
Myopia typically arises from an overly long eyeball or too-strong cornea/lens, focusing distant objects in front of the retina. Nearby objects may still be clear because their diverging rays need more convergence. The blur for distance is the clinical signature.
- Image before retina
- Distant blur
Investigation brief
Plan the question before you open the lab
The brief mirrors the prerendered page: driving question, competing predictions, variable roles, governing laws, setup, analysis and extension prompts remain visible and in this order.
Driving question
A myopic (near-sighted) eye can't relax its focus enough to see distant objects sharply — its far point is a finite distance instead of infinity. Does a more severe myopia (a closer far point) require more or less corrective lens power?
Predictions to weigh
- A closer far point needs less corrective power.
- Corrective power doesn't depend on how close the far point is.
- More — a closer far point needs a stronger diverging lens to bring distant objects into the eye's limited focusing range.
Variable roles
What you set:
- Far point (cm)
What you measure:
- Corrective power P (D)
How the investigation runs
- Open the myopia preset and press Reset. This eye's far point is fixed at 70 cm — anything beyond that appears blurred.
- Enable the corrective-power readout.
- Set the eye's far point for each trial (exploring different myopia severities) and record the corrective lens power needed.
Governing equation
Myopia Corrective Power — P = 1/f (corrective)
A diverging corrective lens images a very distant object (at infinity) exactly at the eye's own far point, so its power is P = −1/far point(m) — negative diopters, growing stronger as the far point moves closer.
What the printable worksheet asks students to work out
- For one trial, compute P = −100/far point (cm), giving diopters. Compare to the table.
- Explain why P comes out negative — myopia is corrected with a DIVERGING lens, which images a distant object (effectively at infinity) at the eye's actual far point instead.
Where this shows up beyond the lab
- Eyeglass prescriptions for myopia are given in negative diopters (like −2.00 D) — bigger magnitude means more severe near-sightedness (a closer far point). Explain, using your data, why someone with a far point of 50 cm needs a stronger prescription than someone with a far point of 100 cm.
- Contact lenses sit directly on the eye, while glasses sit a few cm in front of it — a small but real difference in effective focal length. Why might an optometrist prescribe a slightly different power for contacts versus glasses for the same person?
- AP Physics 2 — Unit 13: Geometric Optics
- General High School Physics — Light & optics
- NGSS High School Physics — Wave properties
- Welcome to Myopia
- Select the eye
- Press Play
- Image in front of retina
- Open the Properties panel
- You did it!
Open the interactive simulation to build the scene, press Play, and explore with live measurements and a guided tutorial.